See Section 27.7.3 for rectangles in space.
The rectangle creates rectangles.
If the arguments varc and vard are given, then C and D will be assigned to them.
| rectangle(0,1+i,1/2) | 
 
| rectangle(0,1+i,-1/2) | 
 
| rectangle(0,1+i,-1/2,C,D) | 
 
| affix(C),affix(D) | 
| 
 | 
Given rectangle(A,B,k), Xcas computes D by affix(D)=affix(A) + k eiπ/2(affix(B)−affix(A)). If k is complex, then rectangle draws a parallelogram.
| rectangle(0,1,1+i) | 
